Hi, already thinking ahead to my next “project” I’ll have some spare epoxy so want to give the home glue up thing a try.
Thinking hot wire, I’ve got a dimmer switch, guitar string, croc clips, wire, springs eyelets ect and all knocking around in one of my “may come in useful one day” piles, and plenty of wood off cuts.
I had a look in the electrical shop for a transformer, most only go up to 12V, but 2 caught my eye,
One rated at 15v, max 4.5Vamp and the other 25v max 9.5Vamp, will these be any good. do I need light bulbs for risistance ???
Cheers.
Yeah it’s a bit of search to get one, mine is actually a generic laptop charger which has variable settings(and plugs for different laptops -sweeeet-) in your case probably both of those will work. I don’t use a lightbulb for resistance because I am using steel wire instead of NiCr. I have tried guitar strings but they break easily. Check you local tackle shop for some single strand steel wire as pictured above.
was one of those Ikea 24v slider-dimmer setups, hooked it to the hotwire and switched it on and got sparky with it… I dunno, maybe it was just a bum dimmer, maybe it was my karma…
This might be redundant, but if someone gets some value out of it that’s cool.
Remember that Watts = Volts x Amps.
So a 12v 4amp setup and a 24v 2amp setup are running equivalent power. And that sounds like the kind of ballpark we are aiming for.
Cheers,
Yes, but (also redundant)…
Amps = Volts/Ohms(resistance)
and
Watts = (Amp) x (Amps) x Ohms
So to get the full power (48 watts) out of the 12V/4A setup, the (hot) resistance of the hot wire will need to be 3 ohms. The (hot) resistance of the hot wire for the 24V/2A setup will have to be 12 ohms.
In either case, a higher resistance (larger guage wire and/or increased length) for the hot wire will result in less than rated power actually supplied, and a lesser resistance (i.e. smaller wire guage and/or shorter length) will exceed the power rating of your supply (leading to its premature death).
Hence you have to choose the appropriate combination of wire composition, wire guage, and wire length for your hot wire to match it to your power supply so you can get full power from the supply. Once you have configured your system to achieve maximum power, it is easy to decrease the power that is supplied to the hotwire by reducing the voltage or increasing the resistance of the hotwire.
I think those two might be a bit lightweight for the job. My nichrome hotwire runs at 1 to 2 amps around 12v, so that would need a 24VA transformer(?). If your transformer is underspecced it will heat up until it starts smoking, found that one out from experience. I’m not an expert on this stuff so you might want to ask someone who knows their stuff to be safe.
Maplin does a 12v 30va toroidal mains transformer which is rated at up to 2.5A if you connect the 2 output coils in parallel.
The hotwire I’m using is the stuff they sell in model shops for cutting foam with, guage seems to be about halfway between the thickest and thinnest guitar strings you can get if that’s any help.
Everything on the left side of the transformer is full mains power! Be careful!
Make sure all the components are correct to handle mains AC power.
Make sure you don't leave out the fuse... And make sure it's 2amp. Unless you want to eletrocute yourself and burn down your house.
Don't try to build it unless you know exactly what you are doing. It's about as simple as circuitry gets, I managed it base on high-school electric tech classes, so it's not a hard one.
Recheck everything before giving it a test run.
You can test it without a hotwire bow. Just by fiddling with the dimmer switch and keeping an eye on the indicator light.
I’m working on mine still, at the slow pace that being broke kind of dictates–just need a battery charger–I am correct in going for one that is 12 volts, and 10 or 12 amps?
Also, is it the decided consensus that a new guitar string .33mm (D’Addario) is going to break as soon as I start?
My tensioner is a bungee I had in my car. It goes downhill from there technology-wise. I’m kind of ectatic too as long as it works!
12 volts, 10 amps might be a bit too hot - but I reckon you can compensate by using a thicker wire (if you dont have current control, eg dimmer switch).
FWIW the one I made was way cheaper than anything I could have bought.
I had bad experience using a bungee for tensioning and switched to a slightly stiffer spring and tensioner - less than AU$5 for both at the local hardware shop.
I hear you re money That, and time, have been the biggest two things slowing me down.
Woody, that last one with the inclination is sooooo on the money… coulda used that one this weeked workin with a buddy on some SUB blanks… gaatttttttt… shoulda checked here first…
That, and time, have been the biggest two things slowing me down.
